A command takes a series of arguments, stdin/out/err pipes and returns an error code on completion. time prefixes a pipeline ( the most basic case being a sing

A command takes a series of arguments, stdin/out/err pipes and returns an error code on completion. time prefixes a pipeline ( the most basic case being a single command without a pipe into another ), a command block { ... } a subshell block ( ... ), a for statement, an if statement, just whatever really. This "time" would output how long "a" took to run: /usr/bin/time a b c | { d e ; f g ; } | h i ; This "time" outputs how long the pipeline "a", "d", "f", and "h" took to run: time a b c | { d e ; f g ; } | h i ; This is a syntax error: /usr/bin/time { d e ; f g ; } This returns how long the command group takes to run: time { d e ; f g ; } Further examples: $ time sleep 10 | sleep 1 ; real 0m10.073s user 0m0.000s sys 0m0.000s $ time sleep 1 | sleep 10 ; real 0m10.003s user 0m0.000s sys 0m0.000s $ /usr/bin/time sleep 10 | sleep 1 ; 0.00user 0.00system 0:10.00elapsed 0%CPU (0avgtext+0avgdata 1796maxresident)k 0inputs+0outputs (0major+80minor)pagefaults 0swaps $ $ /usr/bin/time sleep 1 | sleep 10 ; 0.00user 0.00system 0:01.00elapsed 0%CPU (0avgtext+0avgdata 1808maxresident)k 0inputs+0outputs (0major+82minor)pagefaults 0swaps Note the two /usr/bin/time's output their timing information as soon as the first command is done, but the pipeline doesn't return until both commands have exited. > hope this rant helps in some way